1. Field of the Invention
This invention relates to the field of computer-based system configuration.
2. Background Art
Configuring a system refers to the process of selecting and connecting components to satisfy a particular need or request. If a system is based on a limited number of components, the process of configuring the system can be relatively straightforward. For example, the purchase of an automobile requires a salesperson to configure a system (automobile and assorted options) to satisfy a customer's request. After selecting from a plurality of models, the salesperson completes the transaction by selecting options to configure and price an automobile. The configuring of such a simple system can be accomplished with a pencil and paper.
As system specifications become more customized and varied, configuration alternatives increase and the task of configuring a system becomes more complex. This increased complexity has resulted in a need for computer-based assistance with the configuration process. Early computer-based systems expand independently-generated configuration orders for systems into manufacturing orders. They do not address the actual need for computer-based tools prior to the order expansion. That is, they do not address the actual generation of a system configuration based on needs and/or request input.
An example of a complex system is a desktop computer system. The available configuration alternatives of a computer system are numerous and varied, including alternatives available when choosing the microprocessor, motherboard, monitor, video controller, memory chips, power supply, storage devices, storage device controllers, modems, and software.
Configuring a desktop computer system requires that a selected component is compatible with the other components in the configured system. For example, a power supply must be sufficient to supply power to all of the components of the system. In addition, the monitor must be compatible with the video controller (e.g., resolution), and the storage device must be compatible with its controller (e.g., SCSI interface). A motherboard must have enough slots to handle all of the boards installed in the system.
The physical constraints of the cabinet that houses the system's components are also considered. The cabinet has a fixed number of bays available for storage devices (e.g., floppy disk drives, hard disk drives, or tape backup units). These bays have additional attributes that further define their use. For example, the bay may be located in the front of the cabinet and provide access from the front of the cabinet. Another bay may be located behind the front-accessible bays, and be limited to devices that do not need to be accessed (e.g., hard disk drive). Bays may be full-height or half-height. Before a storage device can be added to the configuration, a configuration system must identify a bay into which the storage device will be housed. This requires that at least the accessibility and height of the storage device must be examined to determine compatibility with an available cabinet bay.
The connection between a storage device and its controller must be determined based on the location of each. The cable that connects the storage device and its controller must provide compatible physical interfaces (e.g., 24-pin male to a 24-pin female).
A method of establishing a communication pathway in a computer system is known as daisy chaining. Daisy chaining provides the ability to interconnect components such that the signal passes through one component to the next. Determining whether a daisy chain may be established requires that the available logical (e.g., IDE or SCSI) and physical interfaces (e.g., 24-pin) of all elements in a daisy chain be known. In addition, it is important to know whether conversions from the source datatype to the destination datatype are allowed. When a daisy chaining candidate is added to the system, the interconnections and conversions between existing components may be checked to determine whether the new component should be an element of the daisy chain.
The power supply and storage device component examples illustrate the need to define the structural interrelationships between components (i.e., physical and spatial relationships). To further illustrate this notion, consider placing components requiring electrical power such as computer, telecommunication, medical or consumer electronic components into two cabinets. Further, each cabinet has an associated power supply that supplies electrical power to the components inside the associated cabinet. To account for electrical power consumption and the requirement that no power supply is overloaded, the model must comprehend the specific cabinet in which each component is placed and update the consumed power for each cabinet. While the total power available in the two cabinets may be sufficient for all of the components to be placed in both of the cabinets, a component cannot be included in a cabinet if its inclusion would cause the cabinet's power supply to overload. Therefore, the physical placement of the component in a cabinet must be known to make a determination if the subsequent placement of a component is valid. Similarly, any physical connections between these components must be taken into account. Each component's position in the structural hierarchy is used to determine minimal or optimal lengths for the connecting components.
Early computer-based configuration systems employed an approach referred to as the rule-based approach. Rule-based configuration systems define rules (i.e., "if A, then B") to validate a selection of configuration alternatives. Digital Equipment Corporation's system, called R1/XCON (described in McDermott, John, "R1: A Rule-Based Configurer of Computer Systems", Artificial Intelligence 19, (1982), pp. 39-88) is an example of a rule-based configuration system. R1/XCON evaluates an existing independently-generated system order and identifies any required modifications to the system to satisfy the model's configuration rules. The rules used to perform the configuration and validation processes are numerous, interwoven, and interdependent. Before any modification can be made to these rules, the spider's web created by these rules must be understood. Any changes to these rules must be made by an individual that is experienced and knowledgeable regarding the effect that any modifications will have to the entire set of rules. Therefore, it is difficult and time-consuming to maintain these rules.
A possible solution to the problems associated with rule-based systems is a constraint-based system. A constraint-based system places constraints on the use of a component in a configuration. For example, a hard disk drive cannot be added to the configuration unless a compatible storage device controller is available for use by the request storage device. The requirement of a controller is a "constraint" on the hard disk drive.
While existing constraint-based systems address some of the shortcomings of rule-based systems, they do not provide a complete configuration tool. Pure constraint-solving systems do not employ a generative approach to configuration (i.e., they do not generate a system configuration based on needs, component requests, and/or resource requests). Existing constraint-based systems use a functional hierarchy that does not address structural aspects associated with the physical placement of a component in a configuration (e.g., memory chip on motherboard or memory expansion board, storage device in cabinet bay, or controller in motherboard slot).
Bennett et al. U.S. Letters Pat. No. 4,591,983 provides an example of a constraint-based system that employs a recognition or verification approach to system configuration instead of a generative approach. That is, Bennett merely validates an independently-configured system. In essence, an order is generated by an independent source such as a salesperson, and Bennett is used to verify that the system contained in the order does not violate any constraints. Bennett does not generate a system configuration based on needs or component requests (i.e., a generative approach). Thus, Bennett does not provide the capability to interactively configure a system by interactively selecting its components.
A model consists of all of the elements that may be included in a configured system. In Bennett the model elements are grouped into an aggregation hierarchy. An aggregation hierarchy creates hierarchical levels that represent a group of elements. Branches from one entry in the current level expand the entry, and the entry is "composed of" the elements in the lower level branches. For example, a desktop computer system is "composed of" a keyboard, a monitor, and a system box. A system box is "composed of" a power supply, motherboard, cards, and storage devices. The "composed of" relationship merely describes the elements that comprise another element. However, the "composed of" relationship does not define the structural relationships between the model elements. The "composed of" relationship does not describe the physical, structural relationships among the elements such as "physically contained inside," "physically subordinate part of," and "physically connected to." Using the desktop computer system previously described, it cannot be determined whether or not a monitor is "physically contained inside" a desktop computer system. A system box is "composed of" storage devices, however it cannot be determined whether one or more of the storage devices are "physically contained inside" the system box.
A functional hierarchy organizes the components of a model based on the purpose or function performed by the components in the model. Each entry in the hierarchy can be further broken down into more specific functional entries. Thus, an entry's parentage defines its functionality, and progression from one level to the next particularizes the functionality of a hierarchy entry.
As used in current configuration systems, a functional hierarchy does not define the structural interrelationships or the physical and spatial interconnections among elements. A functional hierarchy cannot place a storage device in a cabinet bay, a controller card in a particular slot on the motherboard, or a memory chip in a slot on the memory expansion board.
FIG. 2 illustrates an example of a functional hierarchy. HardwareComponent 30 is the root element of the hierarchy. The next level below HardwareComponent 30 (i.e., the second level 49) identifies general functions in the model. For example, ROM 31, Processor Unit 31, Processor 32, Memory 34, Cage 35, Board 36, Connector 37, and Storage Device 38 all perform the function of Hardware Component 30 in addition to their own specialized functions. Processor 33 can be specialized to the function of a SpecialPurpose 40 or GeneralPurpose 41. Special Purpose 40 can be specialized to ArithmeticProcessor 51.
Referring to FIG. 2, it can be seen that a functional hierarchy does not provide the ability to define the structural aspects of the system. For example, there is no capability to determine the contents of Cage 35. The physical and spatial location of MotherBoardSlot 54 descending from Slot 46, in turn descending from Connector 37 cannot be determined from the functional hierarchy. There is no way of determining that MotherBoardSlot 54 is contained by the motherboard. It is not clear from the functional hierarchy definition whether ArithmeticProcessor 51 is located on the MotherBoard 44 or another model element. It cannot be determined whether MemoryChip 42 and ROM 31 are located on MotherBoard 44, MemoryBoard 52, or another model element.
A functional hierarchy does not provide the ability to define actual interconnections between configured instances or the data transfer. That is, that one component is connected to another with compatible logical datatypes (e.g., serial interface) and compatible physical interconnections (e.g., 24 pin). A functional hierarchy only defines the function that a component performs.
Because it does not define the actual connections between the components selected for a configuration, it cannot establish a daisy chain between configured components . Referring to FIG. 2, a functional hierarchy defines Connector 37, Storage Device Controller 53, Floppy Drive 48, and Hard Drive 49 as types of components. To conserve resources, a user may wish to configure a system such that an occurrence of Floppy Drive 48 is daisy chained to an occurrence of Storage Device Controller 53 through Hard Drive 49. However, the functional hierarchy can only reflect that fact that a configured system may contain the functionality provided by Storage Device Controller 53, Hard Drive 49, and Floppy Drive 48. It cannot reflect the fact that an occurrence of Floppy Drive 48 is connected to an occurrence of Storage Device Controller 53 through an occurrence of Hard Drive 49.
Therefore, a functional hierarchy can not traverse a connection pathway to identify structural interrelationships among configured instances. Thus, a functional hierarchy cannot establish a daisy chain. Therefore, a functional hierarchy can not provide the ability to daisy chain components.
Another example of a constraint-based system using a functional hierarchy is provided in the following articles: Mittal and Frayman, "Towards a Generic Model of the Configuration Task," in Proceedings of the Ninth IJCAI (IJCAI-89), pp. 1395-1401; and Frayman and Mittal, "COSSACK: A Constraints-Based Expert System for Configuration Tasks," in Sriram and Adey, Knowledge-Based Expert Systems in Engineering: Planning and Design, September 1987, pp. 143-66.
The Cossack system employs a functional hierarchy-based configuration system. According to Cossack, a system using a functional hierarchy must identify a configured system's required functions. Once the required functions are identified, Cossack must identify some particular component, or components, that are crucial, or key, to the implementation of these required functions. The Cossack representation does not make structure explicit. Further, Cossack does not provide mechanisms for reasoning about or with structural information. Therefore, Cossack cannot make any structure-based inferences. For example, the internal data transfer paths within components are not represented. Therefore, there is no ability to trace data transfer within a component, and no ability to establish a data connection with another element.
A configuration system, whether used to configure a computer system or other system, should provide a tool to interactively: define and maintain a model; define and maintain (i.e., upgrade) a configured system; generate marketing bundles; generate a graphic representation of the physical and spatial locations of the components of the configured system; use the graphic representation to modify or upgrade a configured system; and generate configuration reports (e.g., failed requests, quotations, and bill of materials). Such a system must define the components of a system, the structural relationships among the components (i.e., spatial and physical locations), the actual physical and spatial interconnections of the components, and the constraints imposed by each component.